Phytochemical and In-vitro Antibacterial Activity of the Leaves and Stem Extracts of Sesbania grandiflora (L.) against Some Clinical Isolates

Abstract

Aim: The antimicrobial effect of aqueous and ethanolic extracts from leaves and stem of Sesbania grandiflora (L) against four clinical isolates, namely, Staphylococcus aureus, Escherichia coli, Salmonella enteric and Pseudomonas aeruginosa is the major aim of this research work. Study Design: An experimental study. Place and Duration: This research work was carried out in Sheda Science and Technology Complex (SHESTCO) and Department of Microbiology, University of Abuja, Nigeria, between July, 2013 to July, 2014. Methodology: Using well agar diffusion method, the sensitivity patterns of both crude and different fractional concentrations of ethanolic and aqueous leaves and stem extracts of S. grandiflora were tested. Cold maceration method of extraction was used to extract the plant materials. Fifty grammes of the ground dry sample was placed in 500 cm3 of distilled water and 95% ethanol for 72 hours. After which the supernatant was decanted off, then evaporated to dryness in (Buchi, water bath UK) at 40°C and the crude extract collected was weighed and stored by refrigeration at temperature of 4°C for further uses. Results: The extracts showed significantly varying inhibitory activities against the test organisms as evidenced by the zone diameter of inhibition. The aqueous and ethanolic leaves extract were found to be active against S. aureus in all the concentrations with zone diameter of inhibition ranging between 9.0±00 mm to 24.0±0.21 mm while the ethanolic stem extract was found to be active against S. enterica with zone diameter of inhibition ranging between 11±0.30 mm to 23±0.21 mm. The fractions obtained from the column chromatography were found to be active against S. aureus, with zone diameter of inhibition ranging between 8±0.00 mm to 21±0.00 mm. Ampicillin and Chloramphenicol were used as positive control. Both the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of the extracts ranged between 125 mg/ml to 31.25 mg/ml and 62.5 mg/ml to 15.63 mg/ml respectively. The phytochemical screening divulged the presence of alkaloids, flavonoids, tannins, steroids and terpenoids in both the plant extracts, pholobatannins were absent in aqueous stem extract while anthraquinonnes were absent in both aqueous and ethanolic leaves and stem extracts respectively. Conclusion: S. grandiflora may represent new sources of antimicrobials with stable, biologically active components that can establish a scientific base for the use of plants in modern medicine. This research also justified the scientific basis for the use of the crude leaves extract in the traditional system of medicine for the treatment of diseases especially in treatment of typhoid fever and gastrointestinal infections.